High-speed photographic or cinemato-graphic objective with wide image angle



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StAKUH Kuugv w. ALBRECHT PHOTOGRAPHIC OR CINEMATOGRAPHIC TIVE WITH WIDE IMAGE ANGLE Filed Feb 1959 BED BJEC HIGH-SP 0 June 12, 1962 L5 o f a g I wwwkvvizw INVENTOR WO/ffdm ALBREW 3,038,379 HIGH-SPEED PHOTOGRAPHIC R CINEMATO- GRAPHIC OBJECTIVE WITH WIDE IMAGE ANGLE Wolfram Albrecht, Kreuznach, Rhineland, Germany, assignor to Jos. Schneider & Co., Optische Werke, Kreuznach, Rhineland, Germany, a corporation of Germany Filed Feb. 6, 1959, Ser. No. 791,730 Claims priority, application Germany Mar. 15, 1958 2 Claims. (Cl. 88-57) The present invention relates to a high-speed photographic or cinematographic objective having a wide image angle and a relatively long back-focal distance ranging between 150% and 250% of the overall focal length of the system.

Objectives of this character are of particular value in photographic or cinematographic cameras having additional elements (shutters, deflecting mirrors or the like) located between the last vertex of the objective and the image plane. The invention has for its principal object the provision of an improved objective for such a purpose, adapted to operate with a wide field angle while being of large back-focal length. Other, ancillary objects of the invention are the provision of means in such objectives for correcting chromatic astigmatism and coma as well as other aberrations.

In co-pending U.S. application Serial No. 764,368, filed September 30, 1958, there has been disclosed an objective having a twomember object-side component and a three-member image-side component, the front member of the object-side component being made positively refracting while the associated rear member is negatively refracting, all three members of the imageside component being of positive refractivity. Each of these members is a doublet with the exception of the intermediate member of the image-side component which is advantageously given the form of a biconvex single lens.

In a particularly advantageous embodiment described in the co-pending application, the doublets of each component face each other with their more strongly convex surfaces, their outer surfaces being either concave or substantially plane; also, each doublet turns the concave side of its cemented surface toward the other doublet of the same component.

The present invention has for its object the provision of an optical system of the same general character having an increased field angle and yielding larger images with no increase in dimension, or having smaller proportions for images of a given size, in particular a system in which for equivalent or improved performance the spacing of the vertices is materially reduced.

It has been found, in accordance with this invention, that the above object may be realized by so proportioning the lens thicknesses and air spacings of the elements of the two aforementioned components, including the large diaphragm space between said components, that the total physical length of the system ranges between substantially 5 and 6 times the overall focal length of the objective.

The invention will be described in greater detail with reference to the accompanying drawing the sole FIGURE of which shows, schematically and in axial section, a preferred embodiment.

The objective system shown in the figure of the drawing comprises a first component I on the object side and a second component H on the image side. The front United States Patent 0 (radii r r and thickness 11,) cemented onto a biconcave fourth lens L (radii r r and thickness d;,). Members L L and L L, are two menisci of respectively positive and negative refractivity, the cemented surfaces r r thereof turning their concave sides toward each other.

The first of the three positively retracting members of component II, which is separated from component I by the diaphragm space 11;, consists of a dispersive fifth lens L (radii r r and thickness d cemented onto a collective sixth lens L (radii r r, and thickness d It is separated by an air space d, from a biconvex seventh lens L, of radii r r and thickness d constituting the intermediate member of this component, which in turn is followed after an air space d by a doublet consisting of a positive eighth lens L (radii r r and thickness (112) cemented onto a negative ninth lens L (radii r T14 and thickness (113).

The following table lists representative values of the radii, thicknesses and air spacings of the lenses L -Lg shown in the drawing, given in terms of an overall focal length of numerical value 1 for an objective having an aperture ratio of |1:1.8, an image angle of 66 and a back-focal length of 17, together with the refractive indices n and the Abbe numbers v of these lenses.

Thlcknesses Lens Radii and Air nu v Bpacings I; 12.040 Ll d1 =0. 098 1. 7440 44. 9

r, 1. 707 14..-"--- dz =0. 975 1. 5014 56.5

n 3.061 I d; =0. 010 air space T5 4. 188 L d5 =0. 146 1.5128 57. 2

4, =2. 511 diaphrann space r =+l31. 700 L5 d1 =0.098 1. 6727 32. 2

rs 2.828 Ll di =0. 488 1. 5687 63. 1

dp =0. 005 air space no=+ 4. 746 II L1 1110:0341 1. 6425 58.1

u=0. 005 air space r 2. 440 L; d ==0. 512 1. 5400 59. 7

m=-- 2. 094 L9 d1a=0. 088 1. 7282 28. 3

tim d-5. 687

It will be noted that the total physical length d of the system defined in the foregoing table has a value ranging between 5 and 6, that the back-focal length of this system has a value ranging between 1.5 and 2.5 times the overall focal length, and that the separation d, of the two components of the system has a value ranging between 2.5 and 3.5 times the overall focal length. It may also be mentioned that the first doublet L L, of component 11 is very nearly a plano-convex member.

The invention is not limited to the specific numerical values set forth above, nor to the exact lens configurations shown in the drawing, but may be embodied in various modifications without departing from the spirit lenses and the Abb numbers 11 thereof have numerical values substantially as given in the following table:

and scope of the appended claims. hi k What is claimed is: 5 Lens a F 1. An optical objective system with a back-focal length PM E ranging between substantially 1.5 and 2.5 times the overn 12 040 all focal length of the system, comprising a first, posi- L1 di =0. 09s 1. 7440 44.9 tively refracting meniscus-shaped doublet composed of L, 707 d, 975 1 5014 56 a negative first lens and a positive second lens, a second, r; 3.061 negatively refiracting meniscus-shaped doublet closely I n 3 804 imam air-spaced from said first doublet and composed of a L; a. =0. 410 1.7400 28.2 positive third lens and a negative fourth lens, a third, L (:0'146 mm 5 positively refracting, substantially plane-convex doublet To 0. 791

separated from said second doublet by a relatively wide 15 n +131 700 511 dmphmgmspace diaphragm space and composed of a negative fifth lens LB 1 =0-098 .6727 32.2 tand a positive sixth lens, a biconvex seventh lens closely L6 d8 =0 488 5687 6&1

air-spaced from said third doublet, and a meniscuso -950 shaped fourth doublet closely air-spaced from said sevm=+ 46 =o'oo5 air space enth lens and composed of a positive eighth lens and a 0 II 1 io= .6425 68.! negative ninth lens, the separation of the outermost ver- 5'303 H1005 airspace tices of said components ranging between substantially m=+ 0 5 and 6 times the overall focal length of the system, said 2,094 512 first and second doublets having convex sides facing each v 14 1 1-7282 other and being provided with cemented surfaces turnm=+ 0 ing their concave sides toward each other, the refractive indies: of sid first and hirddlefn esfiei p i y g g l References Cited in the file of this patent mg -oseo SfllSfiOOH an ourt enswerey e refractivity of said cemented surfaces is negative in said UNITED STATES PATENTS first doublet and positive in said second doublet, said 30 1,910,492 Mellor May 23, third and fourth doublets having convex sides facing 1,955,590 Lee '1934 said seventh lens and being provided with cemented sur- 2,548,569 Tone. 1951 faces turning their concave sides toward said seventh lens, 2,594,021 p u et l- Apr. 22, 1952 said diaphragm space ranging between substantially 2.5 2,695,758 Angefl leux 1954 and 3.5 times the overal focal length of the system. 217461351 Tronmel' y 11956 2. An objective system according to claim 1 wherein 2,862,418 Lowenl-hal 2, 1958 the radii r m and the thicknesses and air spacings d -d of said first through ninth lenses 1, 4,, based FOREIGN PATENTS upon a numerical value of unity for the overall focal 1,024,261 Germany Feb. 13, 1958 length of the system, the refractive indices n of said 40 1,154,396 France Oct. 28, 1957 

